Rab-GTPases: dual roles in vesicular transport and viral replication

Productive viral infection is dependent upon post-entry migration of viruses/viral components to sites within a host cell that complement viral deficiencies. Delivery of virions or component proteins to appropriate sites within an infected cell is critical for completing successive stages in viral replication, including release into the cytoplasm, uncoating, genome replication, viral gene expression, assembly and budding. Vesicular transport is essential for steady-state cellular trafficking of membrane-associated proteins. Rab GTPases and their associated effectors are key regulators of vesicular transport pathways. In recent years, Rab proteins have been implicated in the endocytic or exocytic sorting of component viral proteins or intact viruses, most of which are known to be membrane-encapsulated and enveloped. This review will discuss the current understanding of how Rab GTPases and their effectors may regulate individual vesicular transport steps, and detail emerging discoveries examining how specific Rabs and effectors support viral replication.